Update Domain

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden for disclosing side effects. It mentions the types of changes allowed (tracking, TLS, capabilities) but does not disclose potential consequences such as delivery impact, DNS requirements for tracking subdomain, or the rule that at least one capability must remain enabled. This is insufficient for a mutation tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is one sentence of 14 words, front-loaded with the verb and resource, and lists key modification areas without wasted words. It earns a 5.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's moderate complexity (6 parameters, nested object, enums) and rich schema, the description provides a basic overview but lacks context on side effects, permissions, or return behavior. Since there is no output schema, the description should offer more guidance, making it minimally adequate.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema provides 100% description coverage for all 6 parameters, including detailed descriptions for tls, capabilities, openTracking, clickTracking, and trackingSubdomain. The description's mention of 'tracking settings, TLS mode, and capabilities' adds no new semantics beyond the schema, so a baseline score of 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states 'Update an existing domain in Resend' with a specific verb ('update') and resource ('domain'), and further specifies the areas it can modify (tracking settings, TLS mode, capabilities), distinguishing it from sibling tools like create-domain or verify-domain.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies use on existing domains but does not provide explicit guidance on when to use this tool versus alternatives such as verify-domain or get-domain. No exclusions or prerequisites (e.g., domain must exist and be verified) are mentioned.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.